Florida's warm, wet climate makes it an ideal place to grow lush, gorgeous, tropical plants. Unfortunately, some of the non-native plants that thrive here can quickly grow out of control and become an invasive nuisance. One example is the ornamental water hyacinth from South America. In the 1880's they were introduced into Florida and quickly spread, eventually crowding and choking over 100,000 acres of Florida waterways. Continuous control has reduced this number to around 2,000 acres, with scientists researching best practices for further reducing this weed's growth.

Herbicides or mowing can temporarily remove these plants, though they soon grow back. What if there were a sustainable way to reduce water hyacinth and other invasive species with one application and reduce the need for harsh or poisonous chemicals? Enter the USDA's Invasive Plant Research Lab and their biological control agents!

Dr. Ashley Goode, a Research Entomologist at the Lab, specializes in breeding bugs that only eat water hyacinth and releasing the bugs into the environment to attack the weed. Before being released, a biological control species has to be tested to make sure it will only affect the target and not harm other plants. The lab has to grow hundreds of different species of plants—anything closely related to the target, food crops, commercially-valuable landscaping plants—and try to induce their bugs to eat them. Scientists conduct years of testing and permitting to show that the control insect will attack only its target before they release a species for biological control. Scientists have already released several species to control water hyacinth, including a moth and two species of weevil (a type of small beetle).

After release, the next step is to monitor the insects to make sure they are surviving in the wild and to document their impact on the water hyacinth. A few years ago, scientists released a new biological control for water hyacinth, the planthopper Megamelus scutellaris. Goode took us out in the field to take a look at how they are doing.

First we visited a site where Goode had released Megamelus. "Water hyacinth can grow really tall, like up to your head," she tells us. But here the weeds are much smaller, their leaves pocked with distinctive weevil damage and planthoppers on every plant. We next drive half a mile to a "sentinel site," an area where planthoppers have not been released, to see how it compares. "Megamelus can only travel a couple of meters a day" Goode tells us, "but they've managed to make it here." Again, the plants are damaged and infested. The fact that planthoppers have appeared at the second site means that they are managing to survive and spread without human assistance.

Although planthoppers do not entirely eliminate water hyacinths, they do cause a significant decrease in the weed's size. To control the weed "you still have to spray herbicides," Goode tells us, "but maybe half as often." For now, Goode will continue to monitor the Megamelus planthoppers in the wild, and keep looking for insects to eat other invasive weeds.

So what's the next target? "People keep asking about Brazilian pepper," says Goode. "We're on it!"